EQUILIBRATION STUDIES . 2-METHYLTHIOPYRIDINE-N-METHYL-2-THIOPYRIDONE

Equilibration of N-methyl-2-thiopyridone (7) with 2-methylthiopyridine (9) through the catalytic action of N-methyl-2-methylthiopyridinium fluoroborate at 145-188° indicates that 9 is favored in the liquid phase by an enthalpy of 2.6 ± 1.3 kcal/mol. Conversion of this enthalpy difference to the gas phase with correction for differences in kinetic and zero-point energies gives a difference in chemical binding energy between 7 and 9 of 7.6 ± 4.3 kcal/mole in favor of 9. This order of stabilities is contrasted with those observed for the analogous protomeric and oxygen-substituted systems. © 1969, American Chemical Society. All rights reserved.